Automobile heater



Sept. 8, 1953 P. M. FREER 2,651,505

' AUTOMOBILE HEATER Filed May 27, 1950 2 Sheets-Sheet 1,

i MIME) INVEN TOR. 7786/1 Sept. 8, 1953 P. M. FREER u 2,651,505

AUTOMOBILE HEATER Filed May 27, 1950 I 2 Sheets-Sheet 2 INVENTOR. W617.- M e/1 Patented Sept. 8, 1953 UNITED STATES orrlcr.

AUTOMOBILE HEATER Phelps M. Freer, Detroit, Mich. Application May 27, 1950, Serial No. 164,833

-8.4l, filed October :25, 1949, entitled Automobile Heater.

The fundamental object of this'invention is to improve. the'heat transfer. efiiciency of heat exchangers and thus reduce their, size-capacity ratio and cost.

Another object. is to increase the potential or efiiciency nf-heaters of the type set forth in the aforementioned copending application.

Armore detailed object to. increase the area of heattransfer: and. the length and time of passage. of fluids through the heater unit.

Though the invention is not limited thereto, in itsspreierred form, it is included in a heater of the type disclosed, andv claimed in the aiorementioned application wherein a sinuous coil tor heating fluid (ordinarily water) is supported by and upon. the sides of a sheet metal box; which hasothe-r sides that serve to direct fluid. to be heated (ordinarily air) in a sinuous pathbaclr and forth over the.- coil surfaces. Preferably, though the invention is not so limited, the sinuous coil: for water or heating fluid has each or: its plurality of passes disposed horizontally and vertically spaced'from oneanother so:

that a particle flewing through-the coil follows a sinuouspath that i located substantially in a vertical plane. In suchembodiment the sinuunit; as whole: there is a-sinuous interweaving;

of airand:watenv According 11303 01115? present-invention, means are .proyided between adjacent passes of: the coil to increasethezarea :of effective heat transfer and alsc-toreflect.- ar-compound' weaving" or sinuous motion of the airas it fl'ows between the passes. Thisrmotionz is imposedrupon the overall sinuous wearing: of thelair which lies in said substan- 'tially vertical. plane when the coil is positioned I as described, in.- the preceding paragraph. This 'meanspreferably comprises secondary fins in the form a sinuous metal ribbon that has I passes paralleltd'the direction of air flow and normal to the-coil passes.

fitted between adjacent coil passes which may bs/grooved to receive them', the. grooves serving Metal ribbons are to impose a sinuous motion-on the water flowing through the coilpasses. The ribbons have ribs formed in. the surfaceof its passeswhich are inciined ot e o l p ses; ribs cause the 12 Claims. (01. 257-136) preciably greater than the thickness. comprises: a series ofvertic'ally spaced horizonair flowing through the ribbon passes to have a sinuous motion in a plane normal: to the ribbon passes (and parallel to the coil-passes). The inclination of the ribs causes the air to also have a sinuous motion in a plane parallel to the ribbon passes (and. normal to the coil passes). This tortuous motion of the air between the passes increases the length of its path through the heater units and the time of passage, thus increasing the opportunity for heat transfer. The ribbon is of heat conducting material in: contact with the. coil and its passes serve to greatly increase the area capable of transferring hea-tto the air; The ribbons serve an additional function of supporting the coil passes and making the heat transferring material into a rigid mass.

Another feature of the invention resides in a difference inresistance to flow between: the various paths of air flow between the-coil passes and in the shape of the. box. sides. which. direct air flow over the coil passes. This shape is such as. to directair from the paths. of leastrresistance at the extremities of the passes inwardly toward thecenter of the-coil. This feature serves to .slow air passage through. the secondary fins and: promote mixing of the air andeiiicierrcy of the heater.

The inventi'onhasother objects and other features of construction which will bedescribed in ccnneetion with the.- discussion of the-accompanying drawingswherein:

Figure 1 is. aside elevation of a heater core embodying the: invention;

Fig. la is an enlarged view in section of the coil flange supported in a slot: in the box;

Fig. 2 isv an enlarged cross section taken on line 2-2 of Fig: 1 with parts broken away;

Fig. 3 is a section takenon line 33' of Fig. 1 with parts-broken away;

Fig. 4 is an: enlarged view of the parts: shown in the. circle d of'Fig. 2;

Fig, 5 is a development of the: ribbon used in the preferred-- practice of the invention; and

Fig. 6 is. an enlarged section taken on line 66 of Fig. 1

The drawings show an automobile: heater of the type disclosed and claimed in the aforementioned' copending applicationof the present inventor withthe present; invention embodied has-asinuous coil l forfluid, ordinarily'h'ot-iwater from the radiator','.-that is shown. as. substantially rectangular in cross: section with the width ap- The coil tal passes 3- that are sequentially interconnected alternately at? opposite ends by return bends 5 formed in. the coil. The upper and lower ends of thecoil I: serveyof' course;- as the outlet and the inlet: for water and. in a'c'c'ordancewith this inventinn, may-be formed in a novel-manner'to receive the: outlet: and: inlet pipes and 9 for 3 water which are adapted for ready connection or tie into the cooling system of the automobile engine. a

In order to receive the inlet and outlet pipes l and 9, the metal forming the end portions of the coil is shaped into a contour that is adapted to slidably receive the pipes whereby the assembly may be sealingly interconnected, preferably by fusion bonding such as brazing or soldering. The pipes 1 and 9 are illustrated herein as cylindrical hence one surface or side of the coil l is bent transversely outwardly over an arc of about 90 degrees, as shown at H in Fig. 6, and then provided with a radial flange l3. The other or opposite side of the coil 1 is bent around an are of about 270 degrees and provided also with a radial flange I! that is in juxtaposition to the flange IS. The arcs H and I5 are centered on the axis of the pipes l or 9 and of substantially the same radius as these pipes so that they may be closely fitted in the apertures defined by the arcs. The flanges l3 and [1 may be clamped together to give a tight fit and then brazing or soldering metal applied to the joint. During the brazing or soldering operation the metal will flow throughout the arcs i I and I5 as well as between the flanges l3 and I! to provide a tight joint of pipe and coil. It is evident that the pipes I and 9 which are transverse to the direction of flow in the coil passes 3 will be provided with suitable outlet apertures 19 in those portions of their peripheries that are in alignment with the interior of the passes 3.

The coil l and attached pipes I and 9 are fitted within and supported upon a box 2| that is preferably formed of two sheet metal halves or covers 23 and 25 that sealingly engage each other in an overlap or telescopic joint 21 so as to form a substantially leakproof chamber within for the coil l and for fluid to be heated, ordinarily air. The covers 23 and 25 are resiliently held together by bolts and nuts 29 and springs 30 that shoulder on lugs 3| formed on the covers 23 and 25. It will be observed in Fig. 2 that the sides of the covers 23 and 25 containing the joint 2'! are formed with outward bulges 33 that conform to the return bends 5 on the coil l. The return bend coil portions 5 are slipped into these bulges so that the coil l is supported at the opposite ends of the passes 3 upon the box 2|. As indicated best in Fig. 1, the coil I has flanges 35 that extend lengthwise of the passes 3 and certain of these are fitted into suitable return bend recesses or slots 31 formed in the covers 23 and 25 whereby the box furnishes support for certain of the near the top of cover 25 to the outlet aperture 4! formed near the bottom of the cover 25. The

' inlet 39 is formed to deliver airto the space between the first'four passes 3 of the coil 4 and the outlet 41 communicates directly with the spaces i between the last four passes 3 of the coil I, it

being noted that each set of four passes define three vertically spaced and separated passages for air in which the air is traveling in the same direction i. e., to the left adjacent the inlet and. to the right adjacent the outlet. The cover 23 has a bulge 43 formed therein that receives air flowing across the top three passages between coil passes 3 from the inlet 39 and reverses its direction so that it flows to the righ t o g 4 the next three passages between the coil passes 3. Air leaving these last passages enters a bulge 45 formed in the cover 25 and is reversed in direction to flow to the left through the next three coil passages until it reaches the bulge 41 in the cover 23, it being evident that the bulge 41 is not in direct communication with upper bulge 43 because of the fit of the flange 35 of the coil in the cover recess 31. The bulge 4'! reverses the direction of flow of the air and directs it into the last three passages between the coil passes and to the outlet 4! of the unit. As indicated in the other application of the inventor, a fan may be placed at the inlet or outlet of the box 2| to energize an air flow.

It will be recognized that in the present embodiment the air has only four passes and only reverses its direction of flow three times as it passes through the unit though, of course, any desired number of reversals may be had without departing from the invention. The total length of air travel is thus relatively short and the efficiency of heat transfer thereto during its passage through the heater unit is considerably enhanced by the provision of secondary heating fins between the passes 3 of the coil in the air passages. The fins serve to greatly increase the area of heat transfer surfaces; they provide a plurality of separate paths of air flow through each passage as defined by a pair of adjacent coil passes and thereby prevent eddying or stratification; they are formed also to introduce a weaving or tortuous motion of the air passing therethrough thus increasing the effective length of air travel through a passage and increasing the efficacy of heat transfer. The fins are preferably formed so as to interconnect the coil passes 3 to create a relatively rigid mass of heat transfer material and may be received in grooves in the coil passes 3 which serve to create a weaving flow of Water through the passes.

The secondary fins are conveniently formed by a plurality of sinuous metal ribbons 5|, one of which is preferably placed in each passage, i. e., between each pair of adjacent coil passes 3. Each ribbon 5| (Fig. 4) comprises a series of upright passes 53 that are alternately interconnected on opposite ends by return bend sections 55. The return bend sections 55 fit in grooves 5! that are formed in the metal sides of the coil passes 3 and which extend transversely, and preferably normally, to the direction of water flow through the coil passes 3. The upright fins or passes 53 are also transverse to the direction of water flow and are preferably normal thereto and to the surfaces of the passes 3. It will be observed that the grooves 51 extend inside of the coil I so that the water must flow over them, thus imparting somewhat of a sinuous motion to the water. It will also be observed that the fins or passes 53 divide each air passage between a pair of adjacent coil passes into a series of parallel but isolated or separated paths or channels, it being observed that while complete separation is desired benefits of the invention will still be obtained if there is communication between the paths such as might be afforded by apertures in the passes 53.

In order to impart weaving motion to the air flowing through each path or channel, i. e., between each pair of adjacent fins or passes 53, the passes 53 are provided with ribs 59 that may be pressed therein so that adjacent ribs extend out of opposite sides of the pass and so that for adjacent passes the ribs in transverse alignment extend in the same direction as best observed in memos Figs. 3 and 4. It- 1's evident that these ribs will cause a sinuous motion of theair passing-between a :pair offins andithat thisweaving avilrinclude horizontal deviations from a straight-path between the :fins. The ribs59-are 'prefera'blydnclined to the vertical or at an acute'angle to the surface of the passes 3, adjacent "ribs being inclined in opposite'directions with respect to the direction of flow of air-'and the ribs for adjacent passes that are in transverse alignment with each other being inclined in the same-direction. This inclination of the ribs 59 is best illustrated in Fig. 5 which is a'development of a ribbon, the

return bend sections being indicated. by the lines 55. The vertical inclination of the ribs 59- introduces vertical deviations of the'airfrom a straight path and this is superimposed on the'horizontal deviations so that the resultingflow pattern is'of compound sinuosity.

It will be noted that the passes 5'3 of each ribbon 5| transfer loads from one coil pass '3 tothe next so that the ribbons serve to support the coil I. The ribbons 'are'preferably fusion bonded to the coil passes to make the unit a rigid mass. The strength of the ribbon passes 53 for this purpose is,-of course, increased "by the'ribs 59.

It will be observed that the air flowing in the paths at the extremities of "each passage, i. e., between the last fin and there'turn bend sections 5 of the coil I, is likelytobe cooler than the air flowing through the intermediate paths. Hence, means are provided for throwing or directing some of the air that enters these extreme-paths toward the center of the unit. This means preferably comprises inclined portions 51 on opposite sides of the bulges 43, AB-and A] which extend vertically thereof. As will be best appreciated from Fig. 3, the portions-61 baflle the air from the extreme side paths-inwardlytoward'the center of the coil passes so that it is mixed with the Warmer air flowing throughthe central'paths.

The difference between the endmost paths bounded by a fin-'53 and the return-bend-coil sections 5 and the paths -or channels bounded by two fins 53 is an important feature of this invention. The endmost paths, being larger :and having fewer ribs to interfere wtih :air flow,'provide less resistance to air flow. Consequently, each of the endmost paths carries a greater-share of the air per unit of'area than do the intermediate paths. Since the heater functions on the basis of a fixed C. 3?. M., on fixed pressure drop-over the heater, and on fixed temperature, the fact that the end paths carry a. greater volume per unit of area means that air can-move slower through the central paths, thus increasing the efiicacy of heat transfer. 'Thexfaster'moving air in the extreme paths is cooler than that in the central paths but,.as indicated above, equaliaationzis obtained by means of the baffles 6| which mixes this .air with-that flowing through the central paths.

It is evident that the invention may be embodied in-other formsthanthat illustrated herein.

For example, the secondaryflns .canbe used with the housing, a heat conducting-memberbetween 26 a pair of coil passes for --directing.:fluid=1in .a pillrality of separated paths between the coil passes. and converging b'afile means :on the housing r-for "directing fluid leaving themarginal path 'at'an extremity of the pair of passes toward the paths in an intermediate portion of the passes at the same level.

2. In an automobile heater or the like, the combination of a sheet metal box providing .a housing,apair'of'opposite sides of said box having a plurality of spaced outwardly directed v.bulges'iormedtherein, a sinuous-coil for heating fluid within said box having the return-bend portions thereof which interconnect the coil passes :fitted in said bulges whereby said coil is .supportedton said boxsides, saidcoil having flatsurfaced passes that are parallel to each other 'and'w'hich. .are provided with grooves extending across'the surfaces thereof and transverse to the direction of fluid fl-owthrough the pass and which extend inside the-coil to cause sinuous now of -fluid through the coilpasses, a'plurality of sinuous metal ribbons between pairs of said coil passes and fusion bonded thereto and having the return-bend portions thereof seated in said "grooves on opposite surfaces of the coil passes whereby the passes of each of said ribbons-divide thexspac-e between a pair of coil passes into a plurality of separated paths for the passage of fluid to be heated, saidpaths being transverse to 'the direction of fluid flow in the coilpasses, saidribbon passes having ribs formed therein that extend alternately out of opposite sides thereofyand which are generally transverse to the-surfaces of said passes, but which arealternately inclined in opposite directions thereto with respect to the direction ,of flow through said paths, a second pair of ppposite-sides of said box havingpu'twardly extending bulges therein in communication with the sides of said coil and formedto return-bend fluid to be heated flowing out of the paths-between "one pair of coil passes and direct it into the paths between anotherpair "of passes whereby: sinuous flow of fluid to be heated over the coil isobtained, said bulges beingtapere'd inwardly adjacent the "edges of the sides and extremities of the coil passes whereby 'fluid flowing put "of 'the paths at the extremities of the passes is directed toward the paths in a central portionof the coil passes, said second 'pair of opposite sides having coil support surfaces formed therein'and said coil having flanges formed'on thesides -ofsaid passes and supported *on said surfaces, said second pair of opposite sides having an inlet and'an outlet "formed therein for. fluid "to, be heated, the ends of 'said coil being formed to the'shape of conduits for heating fluid and each. having an opening on the side of the coil and conduits extending through said openings and fitted .into said end portions and being sealingly. secured over substantially their entire surface to said end portions, the conduits at opposite ends of said coil serving. as

inlet and .outlet for heating fluid.

In an automobile heater or the like, the

combination ofa sinuous coil having a plurality of passes, undulated walls between pairs of said passes defining sinuous paths for fluid flowing -over the coil .passesQthe marginal paths between the return-bend portions-of the coil and the endmost wa'lls providing less resistance to air flow than the other paths, a pair of converging baffles adjacent the opposite-:marginalpaths for directing fluid flowing throughthe marginal paths so paths, and a housing supporting said baflies and coil.

4. An automobile heater characterized by small size and large capacity comprising a casing of sheet metal, said casing havinga pair of opposite and parallel side walls with transversely extending outwardly formed bulges therein, a sinuous sheet metal coil for water of substantially greater width than thickness and having returnbend sections in said bulges and mounted on said walls, said casing having a second pair of opposite and parallel side walls disposed substantially at right angles to the first pair, one of said second pair of side walls comprising a cover for the casing and being slidably removable therefrom whereby said coil may be slid sideways of its passes into place on said bulges, said sinuous coil having spaced parallel passes, the spaces between said coil passes constituting passages for air, a multiplicity of air passes, eachair pass comprising a multiplicity of adjacent passages, means whereby air in adjacent air passes flows in opposite directions transverse to the flow of water in said coil passes, said means comprising bulges in said second pair of side walls each for receiving air from one air pass and reversing its direction of flow and guiding it into the adjacent air pass, sinuous metal ribbons in the spaces between said coil passes having return-bend sections mounted on said coil passes, said ribbons having sections spaced apart longitudinally of said coil passes and extending transversely thereof to subdivide said passages into a multiplicity of paths for air, said sections having ribs formed thereon on an angle to the,

direction of air flowthrough said paths, adjacent ribs in a section being inclined on angles in opposite directions, adjacent ribs in adjacent sections being formed to extend in the same direction longitudinally of said coil passes wherebyrao they create substantially no restriction to air flow through said paths, means providing an inlet and outlet for said water coil, means providing an inlet and outlet in the casing for air,

.said water inlet and air inlet being located at:

opposite ends of the-casing-whereby counterflow of air and water is provided.

5. The invention as set forth in claim 4 wherein the opposite sides of the bulges in said second pair of side walls are tapered inwardly toward each other to cause air in the marginal paths adjacent theends of the coil passes to be directed inwardly toward the central paths.

6. In an automobile heater having a housing,

a sinuous sheet metal coil for liquid from an.

automobile cooling system supported in said housing, said coil having spaced parallel passes of substantially greater width than thickness and being disposed in said housing so that when said heater is mounted in an automobile said passes are substantially horizontal, the space between adjacent passes constituting passages for air, means providing an inlet for air to communicate with more than one passage at the top of said coil, means on the other side of the coil from said inlet means for receiving air passing through the passages in communication with said inlet means and reversing its direction of flow to cause it to flow through more than one passage below said passages in communication with the inlet means, and means located on the side of said housing opposite said last-mentioned means for receiving air flowing. out of the passagesjinto -which it was directed by said last-mentioned means and reversing its flow to direct it into walls.

more than one passage beneath the previously mentionedpassages.

7. The invention as set forth in claim 6 wherein the air is directedby the inlet means and the reversing means through three passages.

8. The invention as set forth in claim 6 including a series of sheet metal walls perpendicular to said coil passes and parallel to the direction of flow of the air through said passages, said walls dividing said passages into a series of separated paths for air and having ribs pressed therein on an angle to the passes, adjacent ribs in a wall beinginclined in opposite directions and adjacent ribs in adjacent walls being formed to extend in the same direction longitudinally of said coil passes whereby they create substantially no restriction to air flow but cause sinuous motion of the air in the paths in planes parallel to said walls and to said passes.

9. The invention as set forth in claim 8 wherein the air pass flows through three adjacent passages when it passes over the coil in one direction.

10. The invention as set forth in claim 9 wherein said walls constitute passes of sinuous ribbons disposed in said passages and having return-bend sections seated on said coil passes.

11. In an automobile heater the combination of a housing, a sinuous sheet metal coil having a plurality of spaced parallel passes mounted in said housing, said coil having an inlet for coolant from an automobile cooling engine at one end and an outlet for such coolant at the other end, metal walls dividing the spaces between the coil passes into a plurality of paths transverse to the direction of coolant flow through the coil, means in the housing for causing air to flow back and forth across the coil passes in said paths a multiplicity of times, said means causing the air to flowacross more than two coil passes at a time, said means having an inlet for air 'at one end of the housing and an outlet at the other, said air inlet being located at the same end of the housing as said coolant outlet whereby counterfiow of air and coolant is obtained.

12. In an automobile heater or the like, the combination of a sinuous coil having a plurality of passes, and walls of heat conducting material between pairs of said passes, said walls being transverse to the surfaces of the coil passes and transverse to the direction of fluid flow in the coil passes, said walls having projections formed therein so that they are transverse 'to'the coil passes, said projections being adapted to cause compound sinuous flow of fluid between the walls, adjacent projections in adjacent walls being they create substantially no restriction to the flow of fluid between'the walls said projections comprising sla'nted ribs in said walls, adjacent ribs in a wall being slanted in opposite directions with respect to the direction of fluid flow between the PHELPS M. FREER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 953,252 Brinkman Mar. 29, 1910 1,554,924 Shapiro Sept. 22, 1925 1,791,483 Dalgliesh Feb. 3, 1931 1,966,632 Larkin July 17, 1934 2,008,255 Larkin July 16, 1935 2,119,761 Wentworth June 7, 1938 2,211,813 Franco-Ferreira Aug. 20, 1940 2,251,649 Wichmann Aug. 5, 1941 

